1. Field of the Invention
The present invention relates to a thermoelectric conversion element that performs conversion between thermal energy and electric energy by the Peltier effect or the Seebeck effect. The invention also relates to a thermoelectric conversion device using the element.
2. Description of the Related Art
A thermoelectric conversion element includes junctions that alternately connect a p-type thermoelectric conversion material, which has positive charge carriers, and an n-type thermoelectric conversion material, which has negative charge carriers. It performs cooling by the temperature difference between the junctions caused by electric current, or generates an electromotive force by the temperature difference between the junctions. In the thermoelectric conversion element, it is necessary that a high-temperature junction and a low-temperature junction be arranged spaced apart from each other.
Conventionally, a thermoelectric conversion element is, as illustrated in FIG. 17, formed by connecting p-type thermoelectric units 11 and n-type thermoelectric units 12 alternately via inner electrodes 15. The p-type thermoelectric units 11 and n-type thermoelectric units 12 are made of a sintered compact, a molten-solidified substance, a single crystal, or the like of a semiconductor or an oxide material. Each of the inner electrodes 15 becomes either a high-temperature junction or a low-temperature junction alternately, and they are arranged so that the high-temperature junctions are in contact with a high-temperature heat bath portion 13 while the low-temperature junctions are in contact with a low-temperature-side heat bath portion 14. However, as long as a formed solid substance of a sintered compact or the like is used as a thermoelectric substance, it is difficult to reduce the thickness of the element and, moreover, it is impossible to allow the element to have flexibility.
JP 6-29581A discloses a thermoelectric conversion element employing a thin film material. In this element, as illustrated in FIG. 18, p-type thermoelectric conversion parts 1 formed on one surface of an insulating layer (substrate) 6 and n-type thermoelectric conversion parts 2 formed on the other surface thereof (the back surface in the figure) are connected via inner electrodes 5 buried in the insulating layer. In this element, for thickness reduction, the high-temperature junctions and the low-temperature junctions are arranged spaced apart with respect to an in-plane direction, not with respect to a film thickness direction.
Another thermoelectric conversion element having a similar form of connections is disclosed in FIG. 5 of JP 2002-335021A. In addition, JP 8-195509A discloses an improvement in the structure of a thermoelectric conversion device for reducing heat loss.